Antimicrobial Dialkylresorcins from Marine-Derived Microorganisms: Insights into Their Mode of Action and Putative Ecological Relevance

Abstract

<i>Zobellia galactanivorans</i> has been reported as a seaweed-associated or marine-derived species with largely unknown secondary metabolites. The combination of bioinformatic analysis and MS- and bioactivity guided separation led to the isolation of a new antibiotically active dialkylresorcin from the marine bacterium <i>Z. galactanivorans</i>. The antibiotic profile of the new dialkylresorcin zobelliphol (1: ) was investigated and compared with related and naturally occurring dialkyresorcins (i.e., stemphol (2: ) and 4-butyl-3,5-dihydroxybenzoic acid (3: )) from the marine-derived fungus <i>Stemphylium globuliferum</i>. Bacterial reporter strain assays provided insights into the mode of action of this antibiotic compound class. We identified an interference with bacterial DNA biosynthesis for the dialkylresorcin derivative 1: . In addition, the putative biosynthetic gene cluster corresponding to production of 1: was identified and a biosynthetic hypothesis was deduced.